Speed changer mechanism



Oct. 22, 1940. E. E. HARPER SPEED CHANGER MECHANISM Filed Dec. 24, 1938INVENTOR films/-15. Harper; M.

ATTORNEY Patented Oct. 22, 1940 UNITED STATES PATENT OFFICE SPEEDCHANGER MECHANISM Elmer E. Harper, Kansas City, Mo. Application December24, 1938, Serial No. 247,560

1 Claim. (o1. 74-1255) The present invention relates to speed changermechanisms, and an important object in view is to devise improvements inthe means for controlling or varying the rate of transmission-so as topreserve and carry out the speed-changing function uniformly throughoutthe range of the drive afforded by the driving member.

For this purpose I have devised a speed changer construction havingdriving and driven members connected by drive transmission elementswhich are intermittently engageable for the drive transmitting functionand provided with improved control means adapted to vary the driverelation between the elements for obtaining a range of speed ratiosvarying from a zero, or no-drive relation, to a full speed ordirect-drive relation between said driving and driven members.

As one preferred form of construction, I employ a ratchet drivearrangement with a novel control means for controlling the drive oroperative interval of the ratcheting action so as to eliminate anyperiod of lost motion in the operation of the drive member when saidoperation is being carried out at or near the maximum rate of outputspeed.

With the foregoing general objects in view, the I invention will now bedescribed with reference to the accompanying drawing illustrating one ofsuch preferred forms of the improved construction, after which thosefeatures deemed to be novel and patentable will be particularly setforth and claimed.

In the drawing:

Figures 1, 2, and 3 are front, side, and rear elevations, respectively,showing a speed changer device constructed in accordance with thepresent invention;

Figure 4 is a central vertical view of the same on an enlarged scale;

Figures 5 and 6 are other sectional views representing sections taken onthe lines 55 and 6-6, respectively, of Figure 4;

Figure '7 is a fragmentary detail view (on a stilllarger scale) of aportion of the regulating member; and

Figure 8 represents a section taken on the line 8-8 of Figure 7.

Referring to the said drawing in detail, the improved construction isillustrated as comprising a main outer housing member I0, within whichis fitted an inner housing member l2, held in place by screws I l. Thehousing I0 is formed with a bearing l4 fitted with a bushing l5 forjournalling the input drive member comprising a hollow shaft connectionI 6 provided with a pawl-carrying arm I1 on which is mounted a pawl ordriving element I8. The output or wheel 22 arranged in the path ofmovement ofv the pawl l8.

The'central hub portion 24 of the housing l2 provides a bearing for ahollow stem or journal '10 25, which in turn provides a bearing for theouter end of the shaft connection 20 and also a rotary mounting for adisk 26 forming part of the means for controlling the period of thedrive relation between the. pawl I8 and said ratchet 15 wheel 22. Forthis purpose, the disk 26 has attached thereto, at 21, one end of aribbon or shield 28 which is coiled around the periphery of the disk(encircled by a smooth finishing band 26 attached to said periphery) andalso 20 through an opening 30 into a channel 3| formed in the outer sideof the cylindrical portion of the housing H, as clearly illustrated inFigures 4-6. The disk 26 is slightly smaller in diameter than the insideof the housing l2 and the con- 25 permitted to doso according to theadjustment of said ribbon 28. The length of saidribbon is sufiicient toextend into operative or pawlengaging position throughout the completetravel of the pawl, as will be apparent from Figure 6.

The adjusting movement for changing the position of said ribbon 28, asrequired for controlling the action of the driving pawl, is effected bymeans of a knob 35 on a dial member 36 attached by suitable screws 31upon the outer end of the stem or journal 25, said dial member fittingin the cylindrical portion of the housing I0.

It will be apparent from the illustrated construction, as described inthe foregoing, that upon connection of the drive shaft I6 with anappropriate source of power, the rate of drive transmitted therefromthrough the pawl I8 to the ratchet gear 22 will depend upon the settingof the ribbon or shield 28 and the extent of said ribbon which islocated in position for operative engagement with the tail of the pawlelement 3, as represented in Figure 6. It will be understood that thepawl 18 remains in operative driving engagement with relation to thegear or wheel 22 solong as the tail of the pawl is unaffected by orentirely out of engagement with the ribbon 28; therefore as representedin Figure 6, the pawl remains out of driving engagement with the wheel22 during the interval of travel, in the direction of the arrow, fromthe position shown in said Figure 6 until the tail of the pawl passesout of engagement with the end of the ribbon 28 (shown near the bottomof Figure 6), after which for the remainder of the pawls travel, oruntil it again becomes engaged with the ribbon or shield (as at the topof Figure 6) it will be permitted to engage in driving relation with thewheel 22, and thereby drive the shaft element 20 during the sameinterval of said pawls engagement with the wheel 22. It is furthermoreobvious from the construction, as illustrated, that the ribbon or shield28 may be adjusted for the purpose of varying the extent of theoperative period or interval of the pawls engagement with the wheel 22for obtaining any fractional interval of operation, from zero orno-drive relation, as represented by the position of the ribbon 28 inwhich it is extended entirely around the disk 26 or throughout the pathof the pawl l8, up to and including the position in which the ribbon isentirely retracted from the path of the pawls travel, as obtained by thereverse adjustment in which the ribbon is withdrawn substantiallycompletely within the channel 3|, for excluding all engagement with thetail of the pawl, and allowing the latter to remain continuously inoperative engagement with the ratchet wheel 22,--such positionrepresenting the adjustment for maximum full-speed or direct-driverelation between the input and output drive shaft connections.

It is of course apparent that the principle of the speed changingfunction, employing a ratcheting arrangement, is not in itself novel,but all prior constructions so far as known to applicant have involvedsome period of lost output motion when operating at the maximum rate ofoutput speed, due to the fact that the necessary provisions were notmade for obtaining the maximum or full-speed or direct-drive relationbetween the driving and driven members.

As a means for guiding the operator in obtaining the desired ratio ofinput and output speeds, the face of the dial member 36 may beappropriately calibrated for use with an index element 40 carried by oneof the screws H, in connection with which suitable limiting stop meansmay be provided, such as a pin 4| engaging a spacer 42 retained in placeby the index 40 with relation to the margin of the disk 36, for denotingan initial position as represented by the number I on the dial, andwhich may conveniently be made to correspond to the maximum output speedoperation of the device, wherein the pawl 18 is maintained continuouslyin engagement with the ratchet wheel 22. Other settings of the devicefor regulating the ratio of the output speed with relation to the inputspeed will then correspond to the other markings of the dial when it isturned into various positions as, for example, in a range between zeroand I00 and corresponding to as many intermediate speed ratios which areto be obtained by the setting of the dial, and the correspondingadjustment of the ribbon or shield 28, as above explained.

A suitable lubricating passage 44 may be provided in the housing memberID, as represented in Figures 2 and 4, for the attachment of any desiredform of lubricating device for feeding a lubricant into the chamberinside housing member, for obvious purposes.

While I have shown and described thepreferred embodiment of myinvention, it will be 1,;

understood that minor changes in construction, combination andarrangement of parts may be made without departing from the spirit andscope of my invention, as defined by the following claim.

Having described my invention, what I claim is:

A speed changer device comprising a driving member and a driven member,a ratchet wheel in driving relation to said driven member and havingexternal outwardly projecting ratchet teeth, a ratchet pawl actuatedfrom said driving member and traveling in a path outside the peripheryof said ratchet wheel and adapted for engagement with said teeth, andcontrol means comprising a smooth flexible and continuous ribbon mountedfor adjusting movement in a helical path outside the path of said pawland adapted to be projected various extents into the path of the tailportion of the pawl for intercepting said tail portion and retractingthe pawl from engagement with the ratchet teeth and thereby interruptingthe drive to said driven member during such periods of disengagement ofsaid pawl.

ELMERE. HARPER.

